Stroke volume increase to exercise in chronic obstructive pulmonary disease is limited by increased pulmonary artery pressure.

AIMS: This study was designed to investigate the mechanisms by which the right ventricle is able to increase stroke volume (SV) during exercise in chronic obstructive pulmonary disease (COPD). A second aim was to determine whether resting pulmonary artery pressure (Ppa) is predictive of exercise SV. METHODS: 16 COPD patients (GOLD stages II-IV) underwent right heart catheterisation at rest and during exercise. In this group and eight age-matched controls resting and exercise right ventricular SV, end-diastolic volume (RVEDV) and end-systolic volume (RVESV) were assessed by magnetic resonance imaging (MRI). The exercise protocol during both measurements consisted of 3 minutes of cycling in supine position at 40% of maximal workload. RESULTS: In all patients mean Ppa increased significantly in response to exercise (21 (8) vs 33 (11) mm Hg, p<0.01), whereas pulmonary vascular resistance did not change. In the patient group, RVEDV (129 (42) vs 135 (42) ml, p<0.05) and SV (63 (13) vs 69 (14) ml, p<0.05) increased significantly from rest to exercise, but RVESV and RV ejection fraction remained unaltered. In contrast, in healthy controls SV is augmented (81 (22) vs 101 (28) ml, p<0.05) by both increased RVEDV (123 (33) vs 134 134) ml, p<0.05) and reduced RVESV (37 (9) vs 27 (10) ml, p<0.05). Resting mean Ppa was related to SV during exercise (r = -0.59, p<0.02). CONCLUSION: As a consequence of unaltered pulmonary vascular resistance to exercise in COPD patients, Ppa increases and SV response to exercise is limited and results from an increased preload only. Ppa at rest predicts exercise SV.

Sildenafil treatment in COPD does not affect stroke volume or exercise capacity.

In chronic obstructive pulmonary disease (COPD) patients, stroke volume response to exercise is impaired. The aim of the present study was to investigate whether 3 months of sildenafil treatment improves stroke volume and, if so, whether this improvement is related to the pulmonary artery pressure and translated into an improved exercise capacity. A total of 15 stable COPD patients (Global Initiative for Chronic Obstructive Lung Disease stage II-IV) underwent right heart catheterisation at rest and during exercise. Stroke volume was assessed by magnetic resonance imaging (MRI) at rest and during submaximal exercise in the supine position and compared with eight age-matched controls. Additionally, a cardiopulmonary exercise test and a 6-min walking distance test were performed. Exercise tests and MRI were repeated after 12 weeks of oral therapy with 50 mg sildenafil three times daily. Stroke volume in COPD patients was significantly lower than in healthy controls (62+/-12 versus 81+/-22 mL at rest and 70+/-15 versus 101+/-28 mL during exercise). Pulmonary hypertension (PH) was diagnosed in nine patients and was absent in six. Treatment with sildenafil had no effect on stroke volume or exercise capacity. Although the stroke volume was lower in COPD patients with associated PH in comparison with non-PH patients, there was no difference in treatment response between both groups. In the present group of 15 chronic obstructive pulmonary disease patients, a reduced stroke volume was found at rest and during exercise. Neither stroke volume nor exercise capacity were improved by 3 months of sildenafil therapy.